1. Field of the Invention
One or more aspects of the invention generally relate to using large sector size serial ATA (SATA) mass storage devices in a redundant array of independent disks (RAID) array, and more particularly to configuring sector alignment and physical sector size information for the RAID array.
2. Description of the Related Art
A RAID array includes two or more storage devices and appears as a single storage device to an operating system. As the storage capacity of disk drives has increased, the physical sector size has also increased. The physical sector is the smallest unit of data in an ATA storage device. The logical sector is the smallest host addressable unit of data in an ATA storage device. It is desirable to have a larger physical sector size in order to improve the efficiency of error detection and correction for the ATA storage device. It is also desirable to support older disk drives with smaller physical sector sizes along with newer disk drives in a single RAID array.
Recently, optimizations implemented at the operating system level use storage system characteristics to improve access performance by avoiding unaligned writes. In particular, the physical sector size characteristic is used by contemporary operating systems to ensure that writes are aligned to physical sector boundaries. The operating system is configured to use a single physical sector size value to perform optimizations. When a RAID includes storage devices with varying physical sector sizes, it is not possible to report the differing storage system characteristics to the operating system. It is desirable to allow a RAID array that includes storage devices with varying physical sector sizes to benefit from the optimizations performed at the operating system level.
In addition to having different physical sector sizes, different ATA storage devices within a RAID array may also have varying logical sector alignments. Like the physical sector size, the logical sector alignment characteristic is used by contemporary operating systems to ensure that writes are aligned. The operating system is configured to use a single logical sector alignment value to perform optimizations. It is desirable to allow a RAID array that includes storage devices with varying logical sector alignments to benefit from the optimizations performed at the operating system level.